Turbo-generator.



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TURB@ GEN APPLICATION FILE swan 7,1907.

Patented Janulg, 1909.

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ERNST J. BERG, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY,

A CORPORATION or NEW YORK TURBO-GENERATOR.

speincapion of Letters recent.

Patented aan. 19, 190e.

Application filed. September 7, 1907. Serial No. 391,755.

To all whom it may concern:

Bc it known that L-ERNSTJ.' BERG, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New `diferir,have invented certain new and useful improvements in rfurbo Generators,ci which the following is a specilication.

rlhe present invention relates to turbo-generators driven hy multi-stageturbines wherein each stage is provided with independently and usuallywith oppositely rotating wheels,

and has for its object to improve their construction and operation.

ln carrying out my invention the turbine is divided into two stages eachcontaining independently rotating bucket wheels. The adjacent wheels ofthe two stages are mounted on the saine shaft, while the two outerwheels have individual shafts. The steam iiows in any suitable manner asin seriesthrough the admission nozzles and wheels of both stages. Inorder lto preservethe speed relation, o f the shafts and to eectivelyutilize the power developed by the turbines, three electric generatorswound for the saine voltage are employed, the rotating members of 'whichare driven bythe shafts. To ob# tain the highest eiiiciency inoperation, suchv turbines should run at very high speeds. Theelectricgenerator best suited for such purposes is of the induction typehaving a squirrel cage rotorand a ield winding exf cited by alternatingcurrent. rIhe rotor of such a machine can be rotated, practicallyspeaking, at any desired high. speed. This type of machine is not selfexcitingand does not set its own frequency but requires current from analternating current source of supply for the purpose. A synchronousalternator, on the other hand, for mechanical reasons is not adapted tooperate at such high speeds but has the advantage of generating acurrent of definite frequency for a -given speed and number of poles andre quires only a direct current exciter.' The alternatingcurrentderivedl rom this machine may be employed to excite the ield winding ofthe squirrel cage alternators and also to supply current to multi-phaseline conductors. The direct current exciter for the field winding maybedriven by the' turbine shaft or a separate source may' be utilized ifdejsired.Y y.

Since the synchronous alternator is limitsix for example. A governor isor may be provided to regulate the speed oi" the synchronous machine,for example to keep it at substantially 500 P. M.' This machine willthen have a frequency of 1500 per minute as will also the squirrel cagemachines which are connected thereto. Since the lat.- ter machines haveyonly four oles it follows that the shaft speed will be higher than thatof the synchronous machine or 750 R. P. M. at no load and very slightlyhigherwith load. `These gures are given as illustration of my inventionand not as limitations because other vspeeds can be employed if occasiondemands., ln general it may be stated that the induction machines willrun faster than the synchronous machine, all being connected to the samecircuit, andthe speed relation will vary from the above ratio by anamount determined by the I2 (armature copper) loss in the armature ofthe induction machine. Under full load conditions this variation mayamount to about 1%.

rlvhe diameters of the' opposed wheels, one ofwhich drives the rotor ofthe synchronous alternator, may be of the same or substantially thesame' size, or the bucket wheel connected to said rotor may beconsiderably vlarger in which case the' extraction power of the bucketsis greater and the steam economy improved, assuming that `the volume ofsteam to be handled 1s not so great as to impose limitations on the safedesign of the bucket wheel. Where bucket wheels differing greatly indiameter are employed,

intermediate buckets or passages, are pro- -l vided which receive the.steam exhausting from the Wheel of smaller diameter and convey it tothelarger. In this case as before the wheels will rotate in oppositedirections since the intermediates donot reverse the motive Huid butserve to direct it at the best angle of entrance.

It will be seen that Vthe generators while revolving at the differentspeeds best suited 'to their construction have the same frequency and inaddition to being electrically mi"y geared together, so to speak,furnish current to the same bus-bars or other conductors for supplyingcurrent to translating devices.

rlhe steam flows through the four bucket wheels in series, the firstwheel driving one rotor, the secondvand third driving another throughthe same shaft, and the fourth wheel driving the third rotor.

ln the accompanying drawing which illustrates one of the embodiments ofmy invention, Figure 1 is a side elevation partly'in section of amulti-stage turbine directly connected to three electric generators;Fig. 2 is an enlarged detail view showing intermediates for conveyingsteam from one wheel to the next; F ig. 3 is a detail view showing theintermediate and wheel buckets in plan view; and Fig. 4 is adiagrammatic view illustrating the connections of the generators.

' cage winding.

1 indicates thebase of the machine, and mounted thereon are casings 2,each containing a pair of bucket wheels 3, 4 and 5, 6.

vGenerators 7 8 and 9 are also mounted on the base, and their rotors arecarried by shafts 10, 11 and 12. Each shaft is provided with suitablebearings for supporting it. rlhe bearings are carried by pedestals 13resting on the base. rlFhe rotors of generators 7 and 8 are built up' oflaminated iron 14 with conductors 15 embedded therein and connected byend rings 16 to form a squirrel The same winding 17 suces for botharmature and :field and is supported in a laminated structure 18. 'lheconstruction of the synchronous generator 9 is different in that it isprovided with a rotating structure having neld poles 19 provided withcoils 20. rlhese coils receive current vfrom the exciter 21 through theintermediary of brushes and slip-rings 22. The armature comprises alaminated stationary structurev 23 having a winding 24.

rlhe rotor of the generator 7 is driven by the bucket wheel 3. rlherotor of the generator 8 is driven by the bucket wheels 4 and 5,v andthe rotor of the generator 9 is driven by the bucket wheel 6. Steam isadmitted to the turbine by the .conduit 26 which coinmunicates witha'steain chest 27 and suppliesv steam to the sectionalized nozzle 28.The steam after it escapes from the bucket wheel 4 enters a hood-29formed at the side of the casing and is conveyed by the pi e 30 to thesecond or low-pressure stage of tiie machine. After flowing throu h thisstageu it escapes by the exhaust con uit 31 to a condenser-` or to theatmosphere, as desired. As, shown, the steam flows throu h all of thewheels 1n `serios from left to rig t, but if it be desired to change`the output of anygiven wheel it can be passage of the steam.

In Fig. 2 the nozzles 28 are shown on a somewhat larger scale as arealso the bucket wheels 5 and 6. It will be observed that the one bymodifying the bucket wheel 6 isA considerably 'larger in diameter thanthe wheel 5, therefore, it has a higher bucket speed, but owing to thefact that its shaft 12 is electrically geared or tied to the othershafts by the synchronous and induction alternators the shaft speed .islower than that of the shafts 10 and 11. In order to convey steam fromone wheel to the other, intermediate buckets or passages 32 are providedwhich' are carried by the casing of the machine and are supported in anysuitable manner. r1`he relation of these buckets tothe wheel buckets isclearly shown in Fig. 3.

Since the synchronous enerator 9 determines the frequency of a l of thecurrent produced-by the machine as a whole it is necessary to govern itsspeed. To carry out this feature a worm 33 is mounted on the end of theshaft 12 and meshing therewith is a worm wheel mounted on the end of thelow speed shaft 34. 0n the upper end of the shaft is a centrifugalovernor 35 whichcontrols the action of a pi ot valve 361 The pilot valvein turn controls a hydraulic 'motor 37, the piston of which moves a rockshaft 38 to- 'llhe rock shaft is provided with ice. The governingmechanism is shown in a more or less diagrammatic manner to enable thefeatures to be moreav readily understood. lt is evident, however, thatother forms of mechanism can be employed without departing from myinvention.

As the load changes the hydraulic motor will lmove the cam shaft in amanner to change the number of nozzles in service and hence the totaladmission of steam. ince the speed governor is driven by the shaft ofthe synchronous machine the speed of the latter will be the determiningfactor in regulating the steam How.

Referring to Fig. 4, l have shown the generators and their circuits india ram for the purpose f illustration.- 14 indicates the rotatingstructure of thesquirrel cage or induction alternators and r19 the field'poles of the synchronous alternator. The former have four and thelatter has six field poles. The armature structure .23 of thesynchronous alternator is connected b a three-phase connection 40, 41and 42 wit the bus-bars or conductors 43, 44 and 45. The field andarmature 'windings of the squirrel ca e ma.-

chines are wound to produce four fiel poles and the said bus-bars areconnected tovsaid windings in a `manner to cause the field to rotate atsuch a 'speed aswill insure nthe same frequency in the current producedin said machines as inrthe synchronous alternator. In addition `tocarrying current for fixing the frequency of the induction machines andfor maintaining the proper speed relation of the three machines, theconductors of bus-bars 43, 44 and 45 may supply current for any desiredpurpose. It is to be noted that the same 'windings on the inductionmachines serve to excite them and also to generate current and supply itto the busbars or conductors in a manner well understood in theelectrical art.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof,but I desire to have it understood that the apparatus shown 1s 'onlyillustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,"

l. In a turbo-generator, the combination of an elastic fluid turbinecomprising bucket wheels, a shaft driven at relatively high speed by oneof the wheels, an inductionalternator on said shaft, a second shaftdriven at lower speed by another of said wheels, and a synchronousgenerator on said second shaft.

2. In a turbo-generator, the combination of an elastic fiuid turbinecomprising inde- .pendently rotating bucket wheels, a shaft driven atrelatively high speed by one of the f wheels, an induction alternator onsaid shaft, a second shaft driven at lower speed by a wheel, asynchronous alternator on said second shaft, means for maintaining anapproximately constant speed relation between the shafts, and algovernor controlling the flow of motive fluid which is responsivetochanges in the speed of the second shaft.

3. In a turbo-generator, the combination of an elastic fluid'turbinecomprising independent bucket wheels rotating at different speeds, aninduction alternator driven by the wheel having the highest speed, asynchronous alternator driven by the wheel having the. lowest speed, andmeans which maintains the speed relation between the shaftsapproximately constant.

4. In a turbo-generator, the combination of an elastic fluid turbinecomprising` bucket wheels,a shaft driven by one of the wheels at arelatively high speed, a second shaft driven by more than one wheel alsoat a relatively high speed, induction alternators on said shafts, athird shaft driven by1 one \vheela synchronous alternator on said thirdshaft, and means which maintains an approximately constant speedrelation between the shafts. i

5.1In a turbo-generator, the combination of an elastic fluid turbinecomprising bucket wheels, a shaft driven at relatively high speed by oneof the wheels, a second shaft also driven at relatively high speed,induction alternators on said sha ts, a third shaft driven by a wheel, asynchronous alternator on said third shaft, and connections between thealternators which maintain an approximately constantspeed relationbetween them.

6. In a turbo-generator, the combination of an elastic fluid turbinecomprising independently rotating bucket wheels, a shaft driven atrelatively high speed by one of the wheels, an induction alternator onsaid shaft, a second shaft also driven at relatively high speed byothers of said wheels, an induction alternator on said second shaft, athird shaft driven' at lower speed by a wheel, a synchronous alternatoron said third shaft, means which maintains a predetermined speedrelation between the shafts, conduits causing the motive Huid to flowthrough the bucket wheels in series,.and a governor controlling the flowwhich is responsive to changes in the speed of the third shaft.

7. In a turbo-generator, the combination -of an elastic Huid turbinecomprising ind-ependently rotating bucket wheels, and conduits forsupplying motive fluid thereto, an induction generator driven atrelatively high speed by one wheel, a synchronous generator driven at alower speed-by another, and, electrical connections between thegenerators for maintaining an approximately constant speed relationbetween the shafts.

8. In a turbo-generator, the `combination of an elastic fluid turbinecomprising independently rotating bucket wheels, and conduits forsupplying motive fluid thereto, an

induction generator having a certain number of poles driven atrelatively high speed by one wheel, a synchronous generator h aving agreater number of poles driven at a lower speed by another wheel, andconnections between the generators for preserving an approximatelydefinite speed relation between them.

9. In a turbo-generator, the combination of an elastic Huid turbinecomprising inde'- pendently rotating bucket wheels, and a fluidsupplying conduit, with induction and synchronous alternating currentgenerators 'driven by said wheels at different speeds, the inductionalternator being driven at a hi her speed and having a lesser number ofeld poles than the synchronous alternator, and connections between thealternators for exciting the induction alternator and for preserving anapproximately constant speed relation betweenthe shafts.

10. In a turbo-generator, the combination of an elastic fluid turbine,comprisin bucket wheels arranged in groups, a casing or each group,conduits for supplying motive duid generators having a greater number ofeld poles than the other, and electrical connections between theenerators, one of the shafts having a di erent speed from the othershafts and the generators having the, same frequency.

11. In combination, an elastic fluid turbine vcomprising bucket Wheelsarranged for connected.

12. fn a turbo-generator, the combination of an elastic' Huid turbinecomprising bucket wheels one of which is larger in diameter than anotherand has a greater bucket and lower shaft speed, a synchronous generatordriven' by said wheel, an induction generator driven b the other Wheel,independent rotatable siafts for the wheels, passagesreceiving fluidfrom `the wheel of smaller diameter and conveying it to the -one oflarger diameter, and means connecting Vthe generators in parallel to acommon line.

13. fn combination, an elastic Huid turbine comprising bucket wheelsmounted side by side', one having greater bucket and lower shaft speedthan the other, a synchronous 'alternator driven by said wheel, aninduction alternator driven by the other wheel, the synchronousalternator having a larger number of poles than the inductionalternator, and means connecting the alternators in parallel to a commonline.

1 4. fn a turbo-generator, the combination of an elastic fluid turbinecomprising bucket wheels, alternating current electric generators-driventhereby, one of which determines the frequency of the current generated,conductors to4 which the generators are connected, and a governingmechanism regulating the passage offmotive fluid through the bucketwheels that is responsive to the speed of the shaft of the generatorwhich determines the frequency.4

15. In la 'turboege'neraton the combination of an elastic fluid turbinecomprising bucket wheels, an induction alternating currentgeneratordrivenby one of the wheels, a synchronous'j 'alternatingcurrent generator driven byanother Wheel which determines the frequencyof the current producedby the action of both machines, and a governingmechanism which regulates the passage of motive fluidv tothe wheelsthat.y is responsive to the speed of the shaft of the synchronousgenerator: I

16. ln a turbo-generator, the combination of an elastic fluid turbinecomprising lucket Wheels arranged in groups in-separate stage inductionalternator on said shaft, a second shaft driven by one of the outerWheels of the parallel groups, an induction alternator on the secondshaft, a third shaft driven by the other o uter Wheel of said groups, asynchronous alternator on the third shaft which has a larger number ofpoles than the induction alternators and rotates at a correspondinglylower speed, electrical connections luniting the alternators, meanssupplying motive Huid to the turbine, and a governor responsiveV tochanges in the speed of the third shaft which regulates the supply ofmotive fluid.

In witness whereof, I have hereunto set my hand this 6th day ofSeptember, 1907 .4

. 'ERNST J. BERG. g Witnesses:

BENJAMIN B. HULL,

GRACE HARRIGAN.'

